Treat CRI 90 as the minimum for backlit stone, not the target. Below 90, colours look flat or shifted. Our white-channel LED sheets are now rated Ra>95, which gives extra margin on pale onyx, white marble and warm golds — but the slab still decides the final look, so test behind your actual stone.
What CRI does once the light is behind stone
CRI measures how faithfully a light source shows colours compared with natural light. A sheet rated Ra>90 renders colour more accurately than one in the 80s, and Ra>95 narrows the gap to daylight further — and that matters because you see light that has travelled through the slab: warm tones deepen, cool tones wash out, veining goes muddy behind a thicker section.
Why 90 is the floor and 95 is the margin
| CRI band | What you tend to see through stone |
|---|---|
| Below 80 | Colours look dull or shifted; veining loses contrast |
| 80–89 | Fine generally, but soft golds can drift |
| 90–94 | Colours stay close to the real stone in most slabs |
| 95 and above | Extra margin for pale, warm and finely veined stone viewed up close |
The jump from 80 to 90 is visible in most stone. From 90 to 95 the difference is smaller and depends on the slab: it shows most on pale onyx, white marble and stone with warm golds, viewed up close. That is why our white-channel sheets are now built to Ra>95 — you get the margin without having to ask for it.
Ask for the CRI of the white channel you will use, not a headline number: on a colour-changing sheet, white and coloured light are different channels.
Warm white, cool white, and the stone in between
Colour temperature is separate from CRI: warm white around 2700K pulls out golds and ambers, cool white around 6000K sharpens white marble but can make a warm stone look colder than in daylight. Neither suits every slab.
The RGBW BG-0313 offers white only at 3000K or 6000K (512 LEDs, 45W, 5 cores) — pick one when ordering. The RGBCCT BG-0318 carries both whites, 2700K and 6000K, on one sheet (2835, 640 LEDs, 490×245mm, 24V, 50W, 6 cores: V+/R/G/B/warm/cool), so you can tune the mix on site.
Note: a normal 3-channel RGB controller cannot drive the two white channels of a 6-core sheet — confirm the controller handles every channel, with headroom (70–80% controller load, driver ≥ total LED power ÷ 0.8).
What a high CRI will not fix
A CRI 95 sheet in the wrong setup still looks wrong: translucency varies across a slab, no CRI figure evens out a patchy stone, and a dense section stays dim whatever the CRI. The wrong white still looks wrong too — CRI measures accuracy, not warmth. Distance (30–50mm high-density, ~50mm standard) affects evenness, not colour; see our distance guide. Treat CRI as a filter, not a guarantee.
How to check CRI on your sample
Ask for the CRI of the white channel in writing — not a headline number — and test it behind your actual stone at the depth you plan to build, in light close to the finished room. Put a daylight reference next to it: a stone offcut in daylight shows the true golds and veining, and the lit panel should stay close to that, not drift brown or grey. On a dual-white sheet, compare warm and cool on the same slab before locking the choice; the winner is the white that keeps the stone looking like itself.
Checklist before you order
- CRI of the white channel you will use, in writing — 90 minimum, 95+ preferred.
- One fixed white, or a warm-plus-cool mix to tune on site?
- Controller drives every channel, including both whites on a 6-core sheet.
- Test behind your actual stone at the real distance.
- Compare the same slab under warm and cool white before locking the choice.
FAQ
Is CRI 95 worth it over CRI 90?
For pale onyx, white marble and stone with warm golds viewed up close, yes — it is the margin we now build into every white-channel sheet (Ra>95). On dark or heavily patterned stone the difference is smaller, so a sample test and the right white still matter more.
Does CRI matter if my stone is dark?
Less, but it still counts: dark stone passes less light, so errors — and veining — are harder to see.
Can I switch from warm to cool white after installation?
Only if the sheet has both white channels. A dual-white RGBCCT sheet like the BG-0318 lets you retune; a single-white sheet locks in your choice.
Does higher CRI mean a brighter panel?
No. CRI is colour accuracy, not output. Two sheets can share the same wattage yet render stone very differently.
Do I still need a sample if I specify CRI 95?
Yes. A high CRI protects colour accuracy, not how your slab transmits light, which white flatters it, or whether the panel looks even. A sample answers all three.
Start with CRI 90 as the floor and 95+ on the white channel, pick your white — or a tunable warm-plus-cool sheet — and test it behind your actual stone. See our flexible PCB LED light sheets or request a quote with your stone type and panel size.